Synthetic fiber containing powders with the shape of hollow sphere

ABSTRACT

Disclosed is a synthetic fiber, including hollow sphere-shaped particles each formed of any one selected from among an inorganic material, an organic material, or combinations thereof, which is advantageous in terms of a low specific gravity, thereby effectively solving conventional wearing problems.

TECHNICAL FIELD

The present invention relates to synthetic fibers including hollowsphere-shaped particles. More specifically, the present invention isdirected to a synthetic fiber, characterized by having lightweight dueto the hollow particles therein, and various functions according tomaterials constituting the hollow spheres.

BACKGROUND ART

With advances in fiber technologies, functional synthetic fibers havebeen developed to have various properties, for example, the emission offar infrared rays, antibacterial activity, antistatic function,ultraviolet protection, magnetic properties, deodorizing functions, andelectromagnetic wave blocking properties, which are beneficial tohumans. In particular, synthetic fibers having some of the aboveproperties are successfully produced and presently commerciallyavailable.

To obtain fibers having the above properties, there are disclosedmethods of introducing an inorganic particle material capable ofproviding the desired properties into a fiber. However, in cases wherefibers are prepared by means of the above method, the preparationprocesses of fibers have many problems. As well, the prepared fibers mayhave inferior properties. Further, the inorganic particle materialhaving a high specific gravity is introduced into the fiber, whereby thefibers have an increased specific gravity. Hence, clothes made of suchfibers have a heavy feeling upon wearing thereof.

DISCLOSURE OF THE INVENTION

Therefore, it is an aspect of the present invention to alleviate theproblems encountered in the related art and to provide a fiber having alow specific gravity with various functions.

Another aspect of the present invention is to provide a functional fiberhaving various applications, by being easily used for applications ofconventionally used fibers.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is an enlarged photograph of polystyrene microspheres each havinga uniform size,

FIG. 2 is an enlarged photograph of hollow silica spheres; and

FIG. 3 is an enlarged photograph illustrating an internal cavity ofrespective hollow silica spheres.

BEST MODE FOR CARRYING OUT THE INVENTION

Based on the present invention, a synthetic fiber includes hollowspheres each formed of an inorganic material or an organic material.

In cases where an inorganic particle material is used for thepreparation of the synthetic fiber, since the inorganic particlematerial has a specific gravity much higher than that of the resin foruse in the synthetic fiber, the specific gravity of the fiber increasesproportionally with the amount used of the inorganic material.

Therefore, with the aim of solving the problems concerning the highspecific gravity of the fiber, hollow sphere-shaped particles are usedin the present invention. As such, the used hollow spheres should havean apparent specific gravity of 0.5 or less, so that a specific gravityof the fiber is effectively reduced. If the apparent specific gravityexceeds 0.5, the hollow spheres are used in excessive amounts, which hasa negative influence on the physical properties of the fiber.

Moreover, the hollow spheres have a variety of applications, of whichthey mainly serve to reduce the weight of end products and impregnateeffective ingredients, attributable to internal cavities thereof. Inaddition, the hollow spheres have been employed for paints, plastics,rubbers, synthetic woods, cosmetics, fire resisting materials,agricultural chemical-impregnating agents, etc. Representative inorganichollow spheres commercially available are exemplified by silica,alumina, and fly ash, in which particle sizes, shapes, and particle sizedistributions of the hollow spheres depend on the use purposes or pricesthereof.

In terms of a particle size, when a material having a larger particlesize is used for a spinning process, a spinning pack may be plugged orfibers may be cut, whereby the desired yarns cannot be normallyproduced. Also, the produced synthetic fiber is rough on a surfacethereof, and has low strength. Thus, the physical properties of thefiber per se become poor.

Hence, as the size of the hollow spheres decreases, the properties ofthe fibers becomes better or the preparation process thereof becomeseasier. In this regard, the fibers used in clothes of about 1.5 denieror less, which have an average size of about 0.5 μm or less, a 90%particle size of about 1 μm or less and a maximum size of 2 μm or less,may be reliably produced to be suitable for desired applications.However, the above numerical ranges of particle sizes are not strictlyapplied. In particular, in cases of spherical particles, since thecohesion between particles is low, the particles do not cause problemseven though they have slightly larger sizes. Further, if the particleshave smaller sizes, preparation problems rarely surface. Also, fiberswith excellent properties can be obtained.

Among hollow spheres presently commercially available, there exist manyhollow spheres not satisfying the above requirements of the particlesize. This is because such available particle materials are notoriginally intended for fiber applications.

The particle size as mentioned above, resulting from many studies of thepresent inventors, further includes an irregular shape and sizedistribution of particles. If the hollow spheres have practically auniform particle size and are almost perfectly spherical, there is nocohesion between the particles.

Accordingly, even though the hollow spheres have the average particlesize of about 1 μm, serious problems concerning the preparation of thefibers do not occur.

Likewise, organic hollow spheres made of polystyrene are presentlycommercially available. Further, a method of preparing organic hollowspheres is disclosed in U.S. Pat. No. 4,427,836 and Korean Patent No.80123. The organic hollow spheres are used to increase the maskingeffects and whiteness by scattering entered light due to differentrefractive indexes between internal cavities and polymer shellssurrounding such cavities.

To provide other functions in addition to reducing the weight of thefibers, there are proposed methods of using powders of a second materialexhibiting desired functions in the shape of solid spheres, as well as afirst material having hollow spheres. However, the above method isdisadvantageous in that the hollow spheres of the first material, actingto reduce the specific gravity of fibers, and the powders of the secondmaterial having other functions are separately added, and thus a totaladding amount becomes high, which adversely affects the preparationprocess of the fibers. Also, the physical properties of the fiber per semay degrade. Therefore, although being practically usable, the abovemethod is unsuitable.

Further, there are proposed methods of directly preparing hollow spheresby use of a material having a desired function. For example, conductivepowders are used to synthesize hollow spheres. If this happens,synthetic fibers including thusly synthesized hollow spheres areadvantageous in terms of lightweight, and superior antistatic functions.

In addition, hollow spheres having desired sizes may be variouslyprepared. For instance, microspheres of an organic polymer are used asan intermediate to prepare micro particles as in the present invention.By means of organic synthesis, fine spherical particles of the organicpolymer are made, on which a desired material is thinly coated, afterwhich only the internal organic polymers are removed. Thereby,externally coated shells remain, thus obtaining desired hollow spheres.In such a case, the internal organic polymer is removed by a burningprocess or by dissolving it in an organic solvent.

Alternatively, hollow spheres coated with a desired functional materialmay be used as they are.

As for the preparation methods of fibers, an air stream extruding methodmay be adopted, in addition to commonly used spinning methods ofsynthetic fibers.

A better understanding of the present invention may be obtained in lightof the following examples which are set forth to illustrate, but are notto be construed to limit the present invention.

EXAMPLE 1

From commercially available hollow silica spheres having an apparentspecific gravity of 0.15 g/cc, an average particle size of 2 μm and 98%of SiO₂, silica having small sizes were separated, which had an apparentspecific gravity of 0.18 g/cc, an average particle size of 0.65 μm and a90% particle size of 1.3 μm, and a maximum size of 2.2 μm.

Thusly separated hollow spheres were subjected to a master batchpreparation process along with a polypropylene resin, to prepare apolypropylene master batch chip having 10 wt % of hollow silica spheres,which was then further mixed with a polypropylene resin and subjected toa synthetic fiber spinning process, thus preparing a polypropylene yarnof 1.2 denier containing 1.5 wt % of hollow silica spheres.

The prepared fiber had a density ratio of 0.96, in which a density ratiomeans a value obtained by dividing the specific gravity of a yarncontaining hollow spheres by the specific gravity of a yarn containingelvan powder of weight equivalent to the hollow spheres.

EXAMPLE 2

Through an emulsion polymerization, the microspheres of polystyrenehaving a uniform size were synthesized and separated from the emulsion(FIG. 1). Then, TEOS (Tetra Ethyl Ortho Silicate) was hydrolyzed andcoated onto the microspheres, which were then dried. Internalpolystyrene was dissolved in methylene dichloride to obtain hollowsilica spheres (FIG. 2). As for the hollow silica spheres, particles hada uniform size and a diameter of 1.0 μm. To confirm the shape of thesesilica particles, the particles were destroyed and observed. From this,it can be seen that silica is in the shape of hollow spheres (FIG. 3).

The hollow spheres were subjected to the processes same as in example 1,to yield a polypropyele yarn of 1.2 denier containing 1.5 wt % of hollowsilica spheres. The density ratio was 0.94.

EXAMPLE 3

Through a LBL (Layer By Layer) adsorption, 20 nm sized ultrafineparticles of SiO₂ were adsorbed three times to spherical polylatexparticles, to obtain fine particles of polystyrene latex coated withultrafine particles of SiO₂, which were then heat-treated to remove aninternal organic material. Thereby, SiO₂ hollow spheres each having adiameter of 0.6 μm were obtained.

The hollow spheres were subjected to the processes the same as inexample 1, to yield a polypropyele yarn of 1.2 denier containing 1.5 wt% of SiO₂ hollow spheres. The density ratio was 0.96.

EXAMPLE 4

The SiO₂ hollow spheres obtained in example 3 were immersed in a silvernitrate solution to incorporate a silver component into respectivehollow spheres, which were then removed from the solution, dried andburnt to produce SiO₂ hollow spheres each containing 4 wt % of silver.

A spinning process was performed as in example 1, thereby obtaining apolypropylene yarn of 1.2 denier containing 1.5 wt % of SiO₂ hollowspheres each having 4 wt % of silver. The density ratio was 0.97.

To confirm antibacterial activity of the yarn, antibacterial test on E.coli was carried out. From this, the antibacterial activity was found tobe 99% or more. However, the yarn prepared in example 3 had noantibacterial activity.

EXAMPLE 5

The SiO₂ hollow spheres obtained in example 3 were immersed in a SnC₄solution, and separated from a filtrate, and then further immersed in aSbCl₃ solution, neutralized with ammonia, dried, and then heat-treatedat 600° C. for one hour, to obtain a conductive mixture having Sn:Sb of8.8:1 as a weight ratio and SiO₂:[(Sn+Sb) oxide] of 3.2:1 as a weightratio.

The obtained conductive mixture was subjected to a spinning process asin example 1, thereby preparing a polypropylene yarn of 1.2 deniercontaining 1.5 wt % of the conductive mixture. The density ratio was0.97.

The polypropylene yarn had a specific resistivity 1/10,000 lower thanthat of the yarn prepared in example 3, thereby exhibiting an antistaticfunction.

EXAMPLE 6

Zeolite antibacterial material (average particle size 0.5 μm, 90%particle size 1.0 μm, maximum size 1.8 μm) containing 5 wt % of silverwas mixed with hollow silica spheres used in example 2 at a weight ratioof 3:1. By use of thusly obtained mixture and general polyester chips, amaster batch chip containing 10% of an inorganic material was made andmixed with general polyester chips, and then subjected to a spinningprocess, to prepare a yarn of 1.4 denier having 2.0 wt % of theinorganic material and a density ratio of 0.97. By an antibacterial testperformed to confirm the antibacterial activity of the yarn, theantibacterial activity thereof was found to be 99% or more.

EXAMPLE 7

The hollow silica spheres used in example 3 were mixed withethyleneglycol and made in a state of a slurry, which was then subjectedto a polyester chip polymerization process, to prepare a polyestercompound chip containing 2 wt % of hollow silica spheres. The polyestercompound chip was subjected to a spinning process, thus affording apolyester yarn of 1.2 denier containing 2 wt % of hollow silica spheres.The density ratio was 0.97.

Industrial Applicability

As described above, the present invention provides a synthetic fiberincluding hollow spheres. Such a synthetic fiber has physical propertiessuitable for use in clothes and beddings, and lighter weight, comparedto general fibers. Thereby, heavy wearing problems, regarded as theworst of conventional functional fiber products, can be essentiallysolved. Thus, functional synthetic fibers can be variously applied.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A synthetic fiber, comprising hollow spheres each made of any oneselected from among an inorganic material, an organic material, orcombinations thereof.
 2. The synthetic fiber as defined in claim 1,wherein the hollow spheres each have an apparent specific gravity of 0.5or less.
 3. The synthetic fiber as defined in claim 1, wherein thehollow spheres have an average particle size of 0.5 μm or less, a 90%particle size of 1 μm or less, and a maximum size of 2 μm or less. 4.The synthetic fiber as defined in claim 1, further comprising afunctional inorganic material.
 5. The synthetic fiber as defined inclaim 1, wherein the hollow spheres each are coated with a functionalinorganic material.
 6. The synthetic fiber as defined in claim 1,wherein the hollow spheres each are made of a functional inorganicmaterial.
 7. The synthetic fiber as defined in claim 4 wherein thefunctional inorganic material is selected from the group consisting offar infrared-emitting materials, conductive materials, antibacterialmaterials, electromagnetic wave-absorbing materials, ultravioletprotective materials, X-ray blocking materials, deodorizing materials,magnetic materials, and optical materials.
 8. The synthetic fiber asdefined in claim 5, wherein the functional inorganic material isselected from the group consisting of far infrared-emitting materials,conductive materials, antibacterial materials, electromagneticwave-absorbing materials, ultraviolet protective materials, X-rayblocking materials, deodorizing materials, magnetic materials, andoptical materials.
 9. The synthetic fiber as defined in claim 6, whereinthe functional inorganic material is selected from the group consistingof far infrared-emitting materials, conductive materials, antibacterialmaterials, electromagnetic wave-absorbing materials, ultravioletprotective materials, X-ray blocking materials, deodorizing materials,magnetic materials, and optical materials.